This project's long-term objective is to broaden and deepen our understanding of enzyme molecules, which are the essential biological catalysts that make life-processes possible. A two-pronged attack is envisioned, combining X-ray crystallography to delineate the 3-dimensional structure of certain target enzymes with site-directed mutagenesis techniques to create mutants in which specified structural modifications have altered the molecule's properties and function. Among the enzymes to be studied are dihydrofolate reductase, cytochrome- c-peroxidase and cytochrome P450(cam).